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Vulnerability details: VCID-fdum-zfj2-akb4
Vulnerability ID VCID-fdum-zfj2-akb4
Aliases CVE-2019-17026
Summary Incorrect alias information in IonMonkey JIT compiler for setting array elements could lead to a type confusion. We are aware of targeted attacks in the wild abusing this flaw.
Status Published
Exploitability 2.0
Weighted Severity 9.0
Risk 10.0
Affected and Fixed Packages Package Details
Weaknesses (1)
CWE-843 Access of Resource Using Incompatible Type ('Type Confusion')
System Score Found at
cvssv3.1 8.8 http://packetstormsecurity.com/files/162568/Firefox-72-IonMonkey-JIT-Type-Confusion.html
ssvc Attend http://packetstormsecurity.com/files/162568/Firefox-72-IonMonkey-JIT-Type-Confusion.html
cvssv3 8.8 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2019-17026.json
epss 0.42007 https://api.first.org/data/v1/epss?cve=CVE-2019-17026
epss 0.42007 https://api.first.org/data/v1/epss?cve=CVE-2019-17026
epss 0.42007 https://api.first.org/data/v1/epss?cve=CVE-2019-17026
epss 0.42007 https://api.first.org/data/v1/epss?cve=CVE-2019-17026
epss 0.42007 https://api.first.org/data/v1/epss?cve=CVE-2019-17026
epss 0.45521 https://api.first.org/data/v1/epss?cve=CVE-2019-17026
epss 0.45521 https://api.first.org/data/v1/epss?cve=CVE-2019-17026
epss 0.45521 https://api.first.org/data/v1/epss?cve=CVE-2019-17026
epss 0.45521 https://api.first.org/data/v1/epss?cve=CVE-2019-17026
epss 0.45521 https://api.first.org/data/v1/epss?cve=CVE-2019-17026
epss 0.45521 https://api.first.org/data/v1/epss?cve=CVE-2019-17026
epss 0.48798 https://api.first.org/data/v1/epss?cve=CVE-2019-17026
epss 0.48798 https://api.first.org/data/v1/epss?cve=CVE-2019-17026
cvssv3.1 8.8 https://bugzilla.mozilla.org/show_bug.cgi?id=1607443
ssvc Attend https://bugzilla.mozilla.org/show_bug.cgi?id=1607443
cvssv2 6.8 https://nvd.nist.gov/vuln/detail/CVE-2019-17026
cvssv3.1 8.8 https://nvd.nist.gov/vuln/detail/CVE-2019-17026
archlinux Critical https://security.archlinux.org/AVG-1085
archlinux Critical https://security.archlinux.org/AVG-1086
cvssv3.1 8.8 https://security.gentoo.org/glsa/202003-02
ssvc Attend https://security.gentoo.org/glsa/202003-02
cvssv3.1 8.8 https://usn.ubuntu.com/4335-1/
ssvc Attend https://usn.ubuntu.com/4335-1/
generic_textual critical https://www.mozilla.org/en-US/security/advisories/mfsa2020-03
generic_textual critical https://www.mozilla.org/en-US/security/advisories/mfsa2020-04
cvssv3.1 8.8 https://www.mozilla.org/security/advisories/mfsa2020-03/
ssvc Attend https://www.mozilla.org/security/advisories/mfsa2020-03/
cvssv3.1 8.8 https://www.mozilla.org/security/advisories/mfsa2020-04/
ssvc Attend https://www.mozilla.org/security/advisories/mfsa2020-04/
Reference id Reference type URL
https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2019-17026.json
https://api.first.org/data/v1/epss?cve=CVE-2019-17026
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-17016
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-17017
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-17022
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-17024
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-17026
1789214 https://bugzilla.redhat.com/show_bug.cgi?id=1789214
202003-02 https://security.gentoo.org/glsa/202003-02
948452 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=948452
ASA-202001-3 https://security.archlinux.org/ASA-202001-3
ASA-202001-4 https://security.archlinux.org/ASA-202001-4
AVG-1085 https://security.archlinux.org/AVG-1085
AVG-1086 https://security.archlinux.org/AVG-1086
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:esm:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:esm:*:*:*
CVE-2019-17026 Exploit https://gitlab.com/exploit-database/exploitdb/-/blob/main/exploits/windows_x86-64/local/49864.js
CVE-2019-17026 https://nvd.nist.gov/vuln/detail/CVE-2019-17026
Firefox-72-IonMonkey-JIT-Type-Confusion.html http://packetstormsecurity.com/files/162568/Firefox-72-IonMonkey-JIT-Type-Confusion.html
mfsa2020-03 https://www.mozilla.org/en-US/security/advisories/mfsa2020-03
mfsa2020-03 https://www.mozilla.org/security/advisories/mfsa2020-03/
mfsa2020-04 https://www.mozilla.org/en-US/security/advisories/mfsa2020-04
mfsa2020-04 https://www.mozilla.org/security/advisories/mfsa2020-04/
show_bug.cgi?id=1607443 https://bugzilla.mozilla.org/show_bug.cgi?id=1607443
USN-4234-1 https://usn.ubuntu.com/4234-1/
USN-4241-1 https://usn.ubuntu.com/4241-1/
USN-4335-1 https://usn.ubuntu.com/4335-1/
Data source Exploit-DB
Date added May 13, 2021
Description Firefox 72 IonMonkey - JIT Type Confusion
Ransomware campaign use Unknown
Source publication date May 13, 2021
Exploit type local
Platform windows_x86-64
Source update date May 13, 2021
Data source KEV
Date added Nov. 3, 2021
Description Mozilla Firefox and Thunderbird contain a type confusion vulnerability due to incorrect alias information in the IonMonkey JIT compiler when setting array elements.
Required action Apply updates per vendor instructions.
Due date May 3, 2022
Note 
https://nvd.nist.gov/vuln/detail/CVE-2019-17026
Ransomware campaign use Unknown
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Found at http://packetstormsecurity.com/files/162568/Firefox-72-IonMonkey-JIT-Type-Confusion.html
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:A/A:N/T:T/P:M/B:A/M:M/D:A/2025-02-07T12:48:51Z/ Found at http://packetstormsecurity.com/files/162568/Firefox-72-IonMonkey-JIT-Type-Confusion.html
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Found at https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2019-17026.json
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Found at https://bugzilla.mozilla.org/show_bug.cgi?id=1607443
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:A/A:N/T:T/P:M/B:A/M:M/D:A/2025-02-07T12:48:51Z/ Found at https://bugzilla.mozilla.org/show_bug.cgi?id=1607443
Vector: AV:N/AC:M/Au:N/C:P/I:P/A:P Found at https://nvd.nist.gov/vuln/detail/CVE-2019-17026
Exploitability (E) Access Vector (AV) Access Complexity (AC) Authentication (Au) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

high

functional

unproven

proof_of_concept

not_defined

local

adjacent_network

network

high

medium

low

multiple

single

none

none

partial

complete

none

partial

complete

none

partial

complete
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Found at https://nvd.nist.gov/vuln/detail/CVE-2019-17026
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Found at https://security.gentoo.org/glsa/202003-02
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:A/A:N/T:T/P:M/B:A/M:M/D:A/2025-02-07T12:48:51Z/ Found at https://security.gentoo.org/glsa/202003-02
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Found at https://usn.ubuntu.com/4335-1/
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:A/A:N/T:T/P:M/B:A/M:M/D:A/2025-02-07T12:48:51Z/ Found at https://usn.ubuntu.com/4335-1/
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Found at https://www.mozilla.org/security/advisories/mfsa2020-03/
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:A/A:N/T:T/P:M/B:A/M:M/D:A/2025-02-07T12:48:51Z/ Found at https://www.mozilla.org/security/advisories/mfsa2020-03/
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Found at https://www.mozilla.org/security/advisories/mfsa2020-04/
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:A/A:N/T:T/P:M/B:A/M:M/D:A/2025-02-07T12:48:51Z/ Found at https://www.mozilla.org/security/advisories/mfsa2020-04/
Exploit Prediction Scoring System (EPSS)
Percentile 0.97314
EPSS Score 0.42007
Published At July 30, 2025, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2025-07-31T08:09:39.217267+00:00 Mozilla Importer Import https://github.com/mozilla/foundation-security-advisories/blob/master/announce/2020/mfsa2020-04.yml 37.0.0